Hey Gang,

I have a pretty heavy fuel leak coming from drivers side frame rail right underneath the drivers side door on my 96 12v.

I got to work this morning at 8am.
I went out at 2pm for lunch, and bang there it is.
A HUGE puddle of good old #2 under the drivers side of the truck.

Is there a common problem with this happening?
Is it the fuel return line?
When the truck is idling, it drips about the same rate, no increase or decrease.

It has been harder to start lately.
(cranking over more than normal before starting)

any ideas?

 

Wow...either one of the two rubber hoses split or a hole(or rusted out) has occured on one of your steel lines...Sorry that I could not be a little more helpfull...

 

the hard lines on the frame rail on my 98 are stainless. However I hear the rubber lines there like to break. There probbaly more plastic then rubber with those odd push on connectors like the rear has going to the sending unit. If thats the case you can replace it with regular old rubber fuel line and hose clamps. Good luck.

 

Abandon the the stock lines from engine to tank and replace with USCG diesel rated hose.

 

Confirm, please - the WHOLE fuel line, including stainless tubing?? That's a lotta hose. Of course, probably easier than bending line to fit properly through the boxed frame section. Couldn't be any worse than the complete re-plumbing on the 73 D700 dump truck, I guess.

I'll have to check ours out for condition after reading this

 

Yup. The whole line. The tubing tends to crack too, so replacing the whole thing with hose is the way to go. On my regular cab, it was about 12' each for the feed and return line, but measure to make sure. It should take you a couple of hours max. 3/8" feed 5/16" return

 

Ended up, it was leaking from the water in fuel sensor / check valve. (have prime-loc remote fuel filter setup, not that it matters, but the filter is in a different location then stock.)

It leaked all the way down the frame rail and dripped under the drivers side door. Lucky me. (edit: 7/13 6:46pm make that an un-lucky me.) Could have been worse.

 

ok well the leak is back.

listen to this.

I get the truck back from service and its not leaking.
little hard to start tho, (it's getting worse everyday, must give throttle for a quick start)
drives fine home.
park it and go to sleep
get up drive it to work
get there at 8am then i work till 2pm and take lunch
walk out to truck, check cement underneath truck, nothing, dry as a bone.
go to lunch, come back @ 3pm.
park truck, go back to work.
get out of work at 5pm,
walk to truck,
on the way there I notice a huge puddle of diesel. (not happy)
look at the driver side frame rail and yes its leaking from the same exact spot.
So i pop the hood and check the water in fuel light sensor / drain valve / hose, and there all dry as a bone. not leaking at all.
So i cannot firgure out where the fuel is coming from.
try start it up, (turns over 4-5 seconds and nothing)
let off, try starting it again with a little throttle (didn't used to have to do this for the last 4 months)
fires right up, drives great, power, smoke all that.
drive home (40 miles).
park it.
wait 15-20 min.
check driveway / frame rail.
COMPLETELY DRY!

wth?
anyone?

 

I wish it was that easy, I'm not what I would call mechinally inclined.
I'm a diesel newb ... what can i say, i still havent done my kdp.

And im sure as soon as it do it (have the tst kit)
I'll manage to mess something up... or strip a bolt/nut. etc.

I do my fuel/oil/air filters.
and work.

 

About all you can strip are four hose clamps.

Sort of sounds like your tank isn't venting and as the the day heats up the fuel expands causing it to leak. Might try cracking the fill cap during the day and see if anything changes.
Even if it changes you still have a leak to deal with.

 

thanks for the input.
sounds right because its been really hot lately.
and today it was cold in the morning (50-60)
and at lunch / after work it was 75+

 

but, if the tank wasn't venting correctly, would the truck still perform the same? there is no noticeable difference in power or smoke.

*also the truck was completely stock till 365k.
since then its had the mods in the sig, and it was fine for a long time, until the last week, then it started leaking. It's also been dripping more than normal out of the crankcase breather tube. oil level was a little low when I checked it, I actually had to add some. that's a first.

 

bump to the top

 

Look at the fuel pre-heater very closely. My 96 spent a bunch of time up north in some pretty cold climates. Basically the fuel heater was always working to the point it melted some of the wiring going to it. It would leak only with the tank more than half full and would also cause some starting problems because it would let air in and mess up the prime. I live in WA now and bypassed the thing and don't have any more problems. Just my limited experience. CD